<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>AJAX POST 请求</title>
    <style>
        #result{
            width: 200px;
            height: 100px;
            border: solid 2px green;
            border-radius: 5px;
        }
    </style>
</head>
<body>
    <div id="result"></div>

    <script>
        const result = document.getElementById('result');
        //绑定键盘按下事件
        window.onkeydown = function(){
            //发送请求
            const xhr = new XMLHttpRequest();

            xhr.responseType='json';
            //初始化
            xhr.open('GET','http://localhost:8000/json-server');
            //发送
            xhr.send();
            //事件绑定
            xhr.onreadystatechange = function(){
                //判断
                if(xhr.readyState === 4){
                    if(xhr.status >= 200 && xhr.status <300){
                        //手动转换
                        // let data = JSON.parse(xhr.response);

                        // console.log(data);


                        //自动转换
                        console.log(xhr.response);
                        // //处理返回的结果
                        result.innerHTML = xhr.response;
                    }
                }
            }
        }
    </script>
</body>
</html>